(Beyond Pesticides, June 26, 2017) A new report released last week by the U.S. Environmental Protection Agency’s (EPA) Office of the Inspector General finds that the agency must collect and assess information on chemical mixtures and potential synergistic effects in order to improve oversight over pesticide registrations and management of developing herbicide resistance. Synergy results when the mixture of chemicals creates effects greater than the aggregation of individual effects, leading to underestimated toxic impacts on human and environmental health. EPA’s Office of Chemical Safety and Pollution Prevention states it will consider how best to use synergistic effects data for pesticide registration decisions by 2019.

The report, released June 21, 2017, EPA Can Strengthen Its Oversight of Herbicide Resistance With Better Management Controls, is the result of an assessment into EPA’s management and oversight of resistance issues related to herbicide-resistant genetically engineered (GE) crops. The report finds, “EPA uses the pesticide registration process to collect information on human health and environmental risks from pesticides used on herbicide-resistant weeds, but no information is collected regarding synergism.” It states that information on synergy is important because it allows EPA “a greater ability to assess human health and environmental risks combined with real-world pesticide use.” Cited in the report is the case of the herbicide product Enlist Duo, which is a mixture of glyphosate and 2,4-D, and approved for use on GE crops. However, no evaluation of synergy was conducted initially, even though there were patent claims to the U.S. Patent and Trademark Office citing synergism. This was discovered during litigation proceedings of the lawsuit filed challenging the approval of Enlist Duo in 2014. EPA then withdrew its registration approval for Enlist Duo in November 2015. According to EPA, its subsequent review of the synergism claims and data found no synergistic effects. According to the Inspector General, the example of Enlist Duo, “highlights the potential for uncertainty when the EPA does not request data on synergy during the registration process.”

This report follows the 2016 findings by the Center for Biological Diversity (CBD) which report evidence of synergy in the patent applications of nearly 70 percent of multi-ingredient pesticide products (including herbicides, insecticides, and fungicides) approved by the EPA in the last 6 years. CBD’s report found that 140 products with at least two active ingredients were registered between June 2010 and June 2016. Some of the most frequently used herbicides e.g., glyphosate; atrazine; 2,4-D; dicamba; and neonicotinoids, were present in the majority of these patent applications. CBD followed its report with a petition to EPA, asking that the agency require information on pesticide synergy in pesticide-registration applications. That information, according to CBD, was required by regulation from 1984 until 2007, when the agency deleted the provision, calling it unnecessary.

In addition to issues around synergy, the Inspector General’s report also finds a lack of communication and collaboration between the EPA and its public and private stakeholders regarding herbicide resistance management. This is a situation which, “limits the reach of actions proposed and taken by the EPA, the development of meaningful alternatives, and the agency’s ability to proactively respond to herbicide resistance in the field.” The report also notes that EPA does not have measures to track its progress addressing and slowing the spread of herbicide resistance.

The recommendations outlined in the report to assess and develop actions to address and prevent future herbicide resistance problems include, (1) requiring herbicide labels include mechanisms of action, (2) assess the need for more information on synergism, (3) improve data collection and reporting on herbicide resistance, (4) develop performance metrics, and (5) develop a plan for establishing consistent communication with stakeholders. EPA agrees with the recommendations, and the Office of Chemical Safety and Pollution Prevention states that while it does not believe that synergy is related to herbicide resistance management, it is a factor that should be considered in evaluating risk. Further, the Office states, “synergy considerations present a source of uncertainty that might be germane to risk assessments and regulatory decisions in certain instances,” and will consider how best to use this type of information in future evaluations and decisions by June 2019.

To address growing weed resistance, EPA has endorsed a strategy that involves the use of multiple herbicides with differing modes of action, often times within a single product, to combat weeds that have become resistant to a particular herbicide- in this case glyphosate —brought on by the widespread use of the chemical on GE crops. Additionally, farmers are being encouraged to spray their fields with multiple herbicides. However, the effects of these herbicide mixtures have not been fully evaluated and risks are underestimated. As the crisis in weed resistance escalates, threatening crop productivity and profitability, advocates point to organic agriculture as a solution that protects public health, the environment, and farmers’ livelihood. By utilizing ecological pest management strategies, organic practices, and solutions that are not chemical-intensive are the most appropriate and long-term solution to managing unwanted plants, or weeds. Additionally, organic agriculture is an ecologically-based management system that prioritizes cultural, biological, mechanical production practices, and natural inputs. By strengthening on-farm resources, such as soil fertility, pasture and biodiversity, organic farmers can minimize and even avoid the production challenges that most genetically engineered organisms have been falsely-marketed as solving. To learn more about organic agriculture, see Beyond Pesticides Organic Program Page.

All unattributed positions and opinions in this piece are those of Beyond Pesticides.